A major objective is to characterize the reactions of vitamin A derivatives associated with light adaptation and dark adaptation in the retina and to determine the mechanisms by which these reactions are geared into the metabolism of this tissue. Specific aspects to be examined include geometrical isomerization of retinal, biochemistry of cellular retinol-binding protein, cellular retinoic acid-binding protein, 11-cis-retinal-binding protein, and retinoblastoma Y-79 cells. Induction and proliferation of endothelial cells of venules in the vasculature of the retina will also be studied.